Flip Reference

Object Class Reference

Inherits from

Type

Declared in

flip/Object.h

class Object;

flip::Object is the base type to provide custom flip classes. In the following, MyClass denotes a custom flip class.

Member Functions Synopsys

Constructor

Constructs the Object

Destructor

Destructs the Object

operator =

Assigns value

Document Management

document

Returns the document to which the object is attached to

ref

Returns the unique reference number of the object

added

Returns true iff the object was just attached to the document tree

removed

Returns true iff the object was just detached from the document tree

resident

Returns true iff the object was neither attached nor detached from the document tree

changed

Returns true iff the object or one of its children was modified

ancestor

Returns a reference to a parent in the current parent chain of the object

disable_in_undo

Disables the record state modification in history

inherit_in_undo

Inherits the record state modification in history

is_in_undo_enabled

Returns true iff this object modifications are recorded in history

revert

Reverts all the changes made to the object and its children if any

assign

Replaces the content of the object with the content of the provided object

move_assign

Replaces the content of the object with the content of the provided object by moving it

Miscellaneous

parent

Returns the current or previous parent of the object

entity

Returns an entity

Member Functions

Constructor

Object ();                       (1)
MyClass (flip::Default &);       (2)
Object (const Object & other);   (3)
  1. Default constructor.
  2. Default flip constructor. See discussion below.
  3. Copy constructor. Constructs the object with the value of other.

For readability or legacy support, it might be convenient for a new flip object not to be default constructed with 0 values and/or empty containers. One might also want to not provide a default constructor.

At the same time, the flip virtual machine expect to be have a way to construct a flip object, and this newly constructed flip object to have only 0 values and empty containers.

For this reason, the flip::Default constructor was introduced. When the VM is constructing a new object, it will instantiate the flip::Default constructor instead of the C++ default constructor if the former exist. Flip default constructed object shall only have 0 values and empty containers.

Example:

class MyClass : public flip::Object
{
public:
   MyClass () : position (2), content () {}
   MyClass (flip::Default & d) : content (d) {}
   flip::Int position;
   MyOtherClass content;
};
class MyOtherClass : public flip::Object
{
   MyOtherClass () : volume (2) {}
   MyOtherClass (flip::Default & d) {}
   flip::Float volume;
};

Destructor

~Object ();

Destructor.


operator =

Object & operator = (const Object & other);

Copy assignment operator.


document

DocumentBase & document () const;

Returns the document to which the object is attached to.

WARNING: Temporary flip objects are not attached to a document


ref

const Ref & ref () const;

Returns the unique reference number of the object.


added

bool  added () const;

Returns true iff the object was just attached to the document tree.

Example :

void  Observer::document_changed (Note & note)
{
   if (note.added ())
   {
      // A note was added to the document. Create the corresponding
      // view element
      note.entity ().emplace <NoteView> ();
   }
   [...]
}

removed

bool  removed () const;

Returns true iff the object was just detached from the document tree.

Example :

void  Observer::document_changed (Note & note)
{
   [...]
   if (note.removed ())
   {
      // A note was removed from the document. Release the corresponding
      // view element
      note.entity ().erase <NoteView> ();
   }
}

resident

bool  resident () const;

Returns true iff the object was neither attached nor detached from the document tree.

An object can be resident but moved. In this case the iterator pointing to it will allow to detect the move.

Example :

void  Observer::document_changed (Array <Track> & tracks)
{
   auto it = tracks.begin ();
   auto it_end = tracks.end ();
   for (; it != it_end ; ++it)
   {
      Track & track = *it;
      if (it.added () && track.resident ())
      {
         // the track was moved in the container
         // this is the destination position
      }
      if (it.added () && track.resident ())
      {
         // the track was moved in the container
         // this is the source position
      }
   }
}

changed

bool  changed () const;

Returns true iff the object or one of its children was modified.

Example :

void  Observer::document_changed (Note & note)
{
   auto & view = note.entity ().use <ViewNote> ();
   if (note.changed ())
   {
      // one or more properties of the note changed
      if (note.position.changed ())
      {
         view.set_position (note.position);
      }
      if (note.duration.changed ())
      {
         view.set_duration (note.duration);
      }
   }
}

ancestor

template <class T>   T &   ancestor ();
template <class T>   const T &   ancestor () const;

Returns a reference to a parent in the current parent chain of the object.

Note: If an object or its parent is moved from one container to another, this function will always return the current parent, that is not the previous one


disable_in_undo

void   disable_in_undo ();

Disables the record state modification in history of the object and its subtree if any.

Example :

void  add_user (Root & root)
{
   // emplace a new User of the document to store
   // user specific data. User is constructed with
   // the unique user id number given at document
   // creation
   User & user = root.users.emplace <User> (root.document ().user ());
   // we don't want the scroll position in the document
   // to be part of undo
   user.scroll_position.disable_in_undo ();
}

inherit_in_undo

void   inherit_in_undo ();

Inherits the record state modification in history of the object and its subtree if any, from its parent state. This is the default mode.

Note: If the Root object of the tree is in inherited mode, then it is considered as enabled in undo.


is_in_undo_enabled

bool  is_in_undo_enabled () const;

Returns true iff this object modifications are recorded in history. The function recursively search for disabled state starting from the object itself and navigating through the parent objects, if the state is inherited.


revert

void  revert () const;

Reverts all the changes make to the object and its children if any.

Example :

// initially, note.position == 1
note.position = 2;
note.revert ();
// now, note.position == 1

assign

void  assign (const Type & rhs);

Replaces the content of the object with the content of the provided object. Both objects need to be bound to a document for the function to succeed.

Example :

// initially :
// note.position == 1
// note.duration == 3
// note2.position == 2
// note2.duration == 1
note.assign (note2);
// now :
// note.position == 2
// note.duration == 1

move_assign

template <class T>
void  move_assign (T && rhs)

Replaces the content of the object with the content of the provided object by moving it.

Important: The left hand side object needs to be bound to the document but the right hand side object needs not to be bound to a document. This is checked at runtime and will issue a flip_FATAL if this pre-condition is not met.

When the right hand object can be moved, this function should be prefered to assign as it does important optimizations internally.

Example :

// initially :
// note.position == 1
// note.duration == 3
Note note2;
note2.position = 2;
note2.duration = 1;
note.move_assign (std::move (note2));
// now :
// note.position == 2
// note.duration == 1

parent

template <class T>   T &   parent ();
Parent & parent ();

Returns the current or previous parent of the object.

Example:

object.parent <MyClass> ();                  (1)
object.parent ().ptr <MyClass> ();           (2)
object.parent ().before <MyClass> ();        (3)
object.parent ().before_ptr <MyClass> ();    (4)
  1. Return the current parent as MyClass, throws if casting is incorrect
  2. Return the current parent as MyClass, returns nullptr if casting is incorrect
  3. Return the previous parent as MyClass, throws if casting is incorrect
  4. Return the previous parent as MyClass, returns nullptr if casting is incorrect

entity

Entity & entity ();

Returns an entity. Entity are described in details here.

Note: Entities can be made available in all types (including all basic types like Int and Array) by defining the macro flip_ENTITY_LOCATION to flip_ENTITY_LOCATION_TYPE